JP5772185B2 - Pattern defect correcting method and pattern defect correcting apparatus - Google Patents

Description

  The present invention relates to a pattern defect correction method and a pattern defect correction apparatus.

  Lithography technology is used for manufacturing electronic devices such as semiconductor devices. Currently, in mainstream photolithography, a transmissive mask in which a circuit pattern or the like is drawn on a quartz substrate or the like with an absorber such as chromium is used.

  EUV (Extreme UltraViolet) lithography has been developed as a next-generation lithography technology. In this EUV lithography, a multilayer multilayer film of molybdenum and silicon is formed as a reflective layer on a low expansion glass substrate or the like, and a circuit pattern is formed thereon by an absorber such as tantalum nitride, tantalum oxide, or chromium nitride. The drawn reflective mask is used.

  In both cases of photolithography and EUV lithography, a fine mask pattern is not always produced as designed, and various defects may occur. Surplus defects other than the design are called black defects. The black defect is corrected by removing it by some method. Conversely, a partial defect in the design is called a white defect. The white defect is corrected by filling the defective portion with some material.

Currently, a carbon-based material is mainly used as a material for filling white defects in a photolithography mask (see, for example, Non-Patent Document 1). In this case, a hydrocarbon gas such as phenanthrene (C ₁₄ H ₁₀ ) is supplied to the correction site as a raw material, and a carbon-based material is deposited by irradiating an electron beam or the like to cause a chemical reaction locally at a desired position. Let me fix it. Although Non-Patent Document 1 shows an example using a focused ion beam instead of an electron beam, the focused ion beam has some differences such as the inclusion of gallium ions in the deposited carbon-based material. The parts are the same.

  FIG. 6 is a conceptual configuration diagram of a conventional white defect correcting apparatus. A mask stage 52 and a mask stage moving mechanism 53 are installed in the vacuum container 51, and the mask to be corrected 54 is held on the mask stage 52. The vacuum vessel 51 is equipped with an electron beam column 56 and a source gas supply nozzle 57.

  Secondary electrons 60 generated in the irradiated portion by the electron beam 58 irradiated from the electron beam column 56 are detected by a secondary electron detector 59. The generation position of the secondary electrons 60 is specified from the coordinates designated by the mask stage moving mechanism 53 and the coordinates set in the beam scanning mechanism in the electron beam column 56, and the pattern 55 of the mask 54 to be corrected is imaged. .

  A phenanthrene gas 62 is supplied from the source gas supply nozzle 57 to the region including the defect 61 identified from the image, and an electron beam induced chemical reaction is caused by the electron beam 58 to deposit the carbon-based correction material 63 to thereby form the defect 61. Correct it.

  In addition, as a method of using another correction material, a method of supplying a metal compound gas and a carbon compound gas and forming a metal carbide film with energy rays is disclosed (for example, see Patent Document 1). As an example, there is a method of forming and depositing silicon carbide with a laser beam by supplying silane and carbon dioxide gas.

  On the other hand, in an EUV mask, it is known that carbon-based contaminants are deposited on the mask by overlapping EUV light irradiation in the same manner as in an optical element (for example, see Non-Patent Document 2). When carbon-based contaminants are deposited on the EUV mask surface with a thickness of several to several tens of nanometers, the dimensional fluctuation of the transfer circuit pattern on the wafer and the deterioration of the throughput due to a decrease in reflectance become remarkable. Cleansing is necessary.

  As this cleaning method, oxidation dry cleaning using oxygen, ozone, or the like (see, for example, Non-Patent Document 2) and reduction dry cleaning using hydrogen radicals are currently being studied. It has been shown that the carbon-based contamination film can be removed with either method, although the cleaning rate is different.

JP 62-08349 A

sid Rizvi, "Handbook of Manufacturing Technology", published by Taylor & Francis (2005); ISBN, p. 638,0-8247-5374-7 Iwao Nishiyama, “Overview of Extreme Ultraviolet Lithography Technology”, Laser Research, Vol. 36, 673 pages, 2008 H. Nakazawa, H .; Sugita, Y .; Enta, M .; suemitsu, K. et al. Yasui, T .; Itoh, T .; Endoh, Y .; Naritaand M.M. Mashita, “Atomic hydrogen etching of silicon-incorporated diamond-like carbon films prepared laser pulsed deposition”, Diamond Relat. Mater. , 18, 831, 2009

  However, the carbon-based contamination film deposited by EUV lithography and the carbon-based material currently used for defect correction are very similar substances, and the defect-correcting material is also removed by cleaning the carbon-based contamination film. To do.

  In photolithography, deposition of carbon-based contamination does not occur, but various cleanings are repeatedly performed in the mask manufacturing process, which includes ozone-based cleaning such as ozone. Also in this case, there is a concern that the portion to be corrected by the carbon-based material may cause a film loss.

  For example, since a carbon-based material containing silicon is easily dry-etched by, for example, hydrogen radicals (see, for example, Non-Patent Document 3), the same problem occurs in the silicon carbide exemplified in Patent Document 1 above. obtain.

  On the other hand, in addition to the above problems, in the defect correction method in which a correction material is deposited by energy beam induced chemical vapor deposition by supplying a source gas to the correction site and irradiating the energy beam, the meaning of halo ) May occur. Since this halo is generated due to the blur of the energy beam or the influence of secondary electrons generated by the energy beam, this situation will be described with reference to FIGS.

  As shown in FIG. 7A, when the phenanthrene gas 62 is supplied to the correction mask 54 held and fixed on the mask stage 52, an adsorption molecular layer 64 is generated on the correction mask 54. Next, as shown in FIG. 7B, when the electron beam 58 is irradiated, an electron beam induced chemical reaction layer 65 is formed in the irradiated portion.

  Next, as shown in FIG. 7C, the phenanthrene gas 62 is further adsorbed on the electron beam induced chemical reaction layer 65 and the adsorbed molecular layer 64 is overlapped, and the carbon-based correction material 63 is deposited by repeating this. Go.

  However, as shown in FIG. 8A, since the phenanthrene gas 62 is supplied on the correction mask 54, a part of the electron beam 58 collides with the phenanthrene gas molecules 66 in the vacuum and the scattered electrons. It becomes 67, and pours down around the original irradiation area. This is the blurring of the beam here. The scattered electron 67 also generates an electron beam induced chemical reaction layer 65.

  Further, as shown in FIG. 8B, when the electron beam 58 is irradiated on the correction mask 54, secondary electrons 60 are generated at the irradiated portion and emitted to the surroundings. Since the adsorbed molecular layer 64 also reacts with the secondary electrons 60, an electron beam induced chemical reaction layer is also generated around the irradiation region of the electron beam 58. Through the above process, as shown in FIG. 8C, the carbon-based correction material 68 is deposited thinly around the intended correction portion.

  FIG. 9 is an example of halo generated when a patch of carbon-based correction material is deposited by phenanthrene and an electron beam. As shown in FIG. 9, the patch 71 is a carbon-based correction material, and the white dotted line indicates a region 72 where the patch 71 is deposited. The size of the region 72 is 1 μm × 1 μm. It can be seen that the halo 73 is deposited over an area of 1 μm or more around the patch 71.

  Such a halo 73 deteriorates the transmittance or reflectance of the normal portion of the mask or hinders the mask manufacturing process following the correction, and therefore must be suppressed or removed to a minimum.

  Accordingly, it is an object of the present invention to prevent disappearance of defect correction materials in a cleaning process for carbon-based contamination.

From one disclosed aspect, a source gas serving as a silicon supply source and a source gas serving as a carbon supply source are supplied to a correction portion of a lithography mask in a reduced-pressure atmosphere, and an energy beam is irradiated to form silicon by energy beam induced chemical vapor deposition. depositing a carbonaceous material containing the excess deposits occur accompanying the step of depositing a carbonaceous material containing the silicon, and removing with a hydrogen radical, said deposition There is provided a pattern defect correcting method including a step of performing any one of oxidation treatment, nitriding treatment, and oxynitriding treatment on at least a part of the carbon-based material containing silicon .

Further, from another aspect to be disclosed, a source gas supply mechanism that supplies a source gas serving as a silicon supply source and a source gas serving as a carbon supply source to a correction site of a lithography mask in a reduced-pressure atmosphere; and An energy beam irradiation mechanism for irradiating an energy beam, and a mechanism for supplying hydrogen radicals to remove excess deposits accompanying the silicon-containing carbon-based correction material deposited with the energy beam irradiation And a mechanism for forming an etching resistant film by oxidizing, nitriding, or oxynitriding at least a part of the correction site.

  According to the disclosed defect correction method and pattern defect correction apparatus, it is possible to prevent the loss of the defect correction material in the carbon-based contamination cleaning process.

It is a notional block diagram of the pattern defect correction apparatus used for the pattern defect correction method of embodiment of this invention. It is explanatory drawing of the pattern defect correction process of Example 1 of this invention. It is a notional block diagram of the pattern defect correction apparatus used in Example 2 of the present invention. It is explanatory drawing of the pattern defect correction process of Example 2 of this invention. It is a scanning electron micrograph after removing halo using a hydrogen radical. It is a notional block diagram of the conventional white defect correction apparatus. It is explanatory drawing of the conventional white defect correction process. It is explanatory drawing of a halo generating phenomenon. It is explanatory drawing of a halo.

  Here, with reference to FIG. 1, a pattern defect correction method according to an embodiment of the present invention will be described. FIG. 1 is a conceptual configuration diagram of a pattern defect correction apparatus used in a pattern defect correction method according to an embodiment of the present invention, in which an etching resistant film forming gas supply mechanism is incorporated in a conventional pattern defect correction apparatus.

  As shown in FIG. 1, a mask stage 12 and a mask stage moving mechanism 13 are installed in a processing container 11, and a mask 14 to be corrected is held on the mask stage 12. The processing container 11 is equipped with at least an energy beam irradiation mechanism 16, a source gas supply mechanism 17, and an etching resistant film forming gas supply mechanism 18. Further, a secondary electron detection mechanism 19 is provided in the processing container 11, and a correction material etching gas introduction mechanism is provided as necessary.

  Secondary electrons 21 generated in the irradiated portion by the energy beam 20 irradiated from the energy beam irradiation mechanism 16 are detected by the secondary electron detection mechanism 19. The generation position of the secondary electrons 21 is specified from the coordinates specified by the mask stage moving mechanism 13 and the coordinates set in the beam scanning mechanism in the energy beam irradiation mechanism 16, and the pattern 15 of the mask 14 to be corrected is imaged. .

  A source gas 23 containing silicon and carbon is supplied from the source gas supply mechanism 17 to a region including the defect 22 identified from the image, and a chemical reaction is caused by the energy beam 20 to cause a carbon-based correction material 24 containing silicon. To correct the defect 22.

Next, an etching resistant film forming gas is supplied from the etching resistant film forming gas supply mechanism 18, and at least the surface of the correction material 24 is oxidized, nitrided, or oxynitrided to form an etching resistant film. Here, in order to promote the reaction only at a desired site, the energy beam 20 may be irradiated together with the supply of the etching resistant film forming gas. Note that halo is removed using hydrogen radicals before the formation of the etching resistant film.

  As a silicon supply source in the source gas 23, silicon hydride such as silane or disilane, or an organic silicon compound such as tetramethylsilane, tetraethoxysilane, or hexamethyldisilazane is used. When removal of halo becomes a problem, it is desirable to use molecules that do not contain oxygen and nitrogen as the source gas 23.

  In addition, the carbon supply source in the source gas 23 is not limited to phenanthrene, and general materials that cause carbon deposition by energy beam irradiation, such as methyl methacrylate, can be used.

  The carbon supply source and the silicon supply source may be mixed and prepared in advance and supplied from the source gas supply mechanism 17, or each source material is prepared separately and mixed in the process of introducing each gas to the source gas supply mechanism 17. It doesn't matter. Furthermore, two source gas supply mechanisms 17 may be provided to supply each gas separately to the correction site.

  As the etching resistant film forming gas, oxygen gas, ozone gas, water vapor, nitrogen gas, ammonia gas, hexamethyldisilazane gas, and nitrogen dioxide are used. The energy beam 20 is typically an electron beam, but a gallium focused ion beam or a focused ion beam such as helium ion or fullerene molecular ion that causes little damage to the mask may be used.

  Further, although the correction material deposition mechanism and the etching resistant film forming mechanism are installed in the same processing container, in principle, it is not always necessary to perform processing in the same container.

  Hydrogen radicals are generated using a hot filament such as tungsten or molybdenum, a tungsten tube incandescent by electron impact or the like, or electron cyclotron resonance plasma or inductively coupled plasma.

  As described above, in the embodiment of the present invention, after the defect is corrected with the carbon-based correction material containing silicon, the etching resistant film is formed by oxidation, nitridation, or oxynitridation. Since silicon oxide, silicon nitride, and silicon oxynitride are resistant to hydrogen radicals that are candidates for the carbon-based contamination cleaning process of the EUV mask, the defect correcting portion does not disappear in the carbon-based contamination cleaning process.

  Furthermore, carbon-based correction materials containing silicon prior to oxidation and other treatments are easily etched by hydrogen radicals, so even if halo occurs during the correction process, hydrogen radical treatment is performed without breaking the vacuum. This can be easily removed.

  At this time, the film thickness of the corrected part is also reduced by hydrogen radicals. However, the film thickness of the halo part is usually about one-hundred of the corrected part and the deposited film thickness is significantly different, so the effect of the correction is maintained. There is no problem in removing only the halo part. If necessary, a thicker film may be deposited in advance on the corrected portion by the amount of film reduction.

  The halo removal mechanism is installed in the same processing vessel as the deposition mechanism of the correction material by the energy beam and the etching resistant film formation mechanism, but the deposition portion from the vacuum vessel used for deposition to the vacuum vessel used for halo removal is removed from the atmosphere. As long as it can be conveyed without being exposed to, the halo removal process may be performed in a separate processing container.

  Next, with reference to FIG. 2, a pattern defect correcting method according to the first embodiment of the present invention will be described. First, as shown in FIG. 2 (a), a mixed gas 31 of phenanthrene and tetraethoxysilane is supplied from the source gas supply mechanism 17 to the region including the defect 22 specified from the image, and from the electron beam column 32. The electron beam 33 is irradiated. The defect 22 is corrected by depositing a carbon-based correction material 24 containing silicon by causing an electron-induced chemical reaction by irradiation with an electron beam. The acceleration energy of the electron beam 33 is set to 2 keV to 30 keV, and typically, the acceleration energy of 3 keV having a high film formation rate is used.

  Next, as shown in FIG. 2B, an oxygen gas 34 is supplied from the etching resistant film forming gas supply mechanism 18 to oxidize at least the surface of the correction material 24 to form an oxide film 35. Here, in order to promote the reaction only at a desired site, the correction work is completed by irradiating the electron beam 33 together with the supply of the oxygen gas 34. Here, the acceleration energy of the electron beam 33 is 3 keV.

  As described above, in Example 1 of the present invention, an oxide film having resistance to ozone and hydrogen radicals is formed on the surface after depositing a silicon-containing material, which corresponds to the cleaning process of the carbon-based contamination film. Defect correction is realized.

  Next, a pattern defect correcting method according to the second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a conceptual block diagram of a pattern defect correction apparatus used in Embodiment 2 of the present invention, in which a hydrogen radical supply mechanism 40 is provided in the pattern defect correction apparatus of FIG.

  Next, with reference to FIG. 4, the pattern defect correction process of Example 2 of this invention is demonstrated. First, as shown in FIG. 4A, in the same manner as in the first embodiment, a mixed gas 31 of phenanthrene and tetraethoxysilane is supplied from the source gas supply mechanism 17 to the region including the defect 22 specified from the image. Then, the electron beam 33 is irradiated from the electron beam column 32. The defect 22 is corrected by depositing a carbon-based correction material 24 containing silicon by causing an electron-induced chemical reaction by irradiation of the electron beam 33. At this time, the halo 41 is deposited around the correction pattern.

  Next, as shown in FIG. 4B, the hydrogen radicals 42 are supplied from the hydrogen radical supply mechanism 40 to remove the halo 41. Hydrogen radicals 42 were generated by thermal catalytic decomposition of a hot tungsten filament heated to 1800 ° C. with hydrogen gas. Since the film thickness of the halo 41 is significantly different from about one-hundredth of the corrected portion, only the halo 41 can be removed while maintaining the correction effect.

  FIG. 5 is a scanning electron micrograph after removal of the halo using hydrogen radicals. As shown in FIG. 5, it is a patch 45 of a carbon-based correction material, and a white dotted line indicates a region 46 where the patch 45 is deposited. The size of the region 46 was 1 μm × 1 μm, and it was confirmed that halo was removed from the comparison with FIG.

  Next, as shown in FIG. 4C, an oxygen gas 34 is supplied from the etching resistant film forming gas supply mechanism 18 to oxidize at least the surface of the correction material 24 to form an oxide film 35. Here, in order to promote the reaction only at a desired site, the correction work is completed by irradiating the electron beam 33 together with the supply of the oxygen gas 34.

  Thus, in Example 2 of the present invention, after depositing a silicon-containing material and removing the halo, an oxide film resistant to ozone and hydrogen radicals is formed on the surface. Therefore, defect correction corresponding to the cleaning process of the carbon-based contamination film is realized without deteriorating the transmittance or reflectance of the normal part of the mask.

  Note that by increasing the positional accuracy of irradiation with the electron beam, it is possible to prevent the etching resistant film from being formed on the halo portion. In this case, after the defect is corrected by depositing a carbon-based material containing silicon at the correction site, an etching resistant film is immediately formed, and then the halo may be removed.

Here, the following supplementary notes are attached to the embodiments of the present invention including Example 1 and Example 2.
(Supplementary Note 1) In a reduced pressure atmosphere, a source gas serving as a silicon supply source and a source gas serving as a carbon supply source are supplied to a correction portion of a lithography mask and silicon is contained by energy beam induced chemical vapor deposition by irradiation with an energy beam. depositing a carbonaceous material, the excess deposits occur accompanying the step of depositing a carbonaceous material containing said silicon and removing with hydrogen radicals, the silicon to which said deposition A pattern defect correcting method including a step of performing any one of oxidation treatment, nitriding treatment, and oxynitriding treatment on at least a part of the carbon-based material contained .
(Supplementary note 2) The pattern defect correction method according to supplementary note 1, wherein silicon hydride or an organic silicon compound is used as a source gas serving as the silicon supply source .
(Supplementary note 3) The pattern defect correction according to Supplementary note 2, wherein the silicon hydride or the organic silicon compound is any one of silane, disilane, tetramethylsilane, tetraethoxysilane, or hexamethyldisilazane. Method.
(Additional remark 4) The pattern defect correction method of Additional remark 2 characterized by using the molecule | numerator which does not contain oxygen and nitrogen as source gas used as the said silicon supply source .
(Additional remark 5) At least one of oxygen gas, ozone gas, water vapor | steam, ammonia, or nitric oxide is used in any process of the said oxidation process, the said nitridation process, or the said oxynitridation process The pattern defect correction method according to any one of the above.
(Supplementary note 6) The supplementary note 5, wherein the carbon-based material containing the deposited silicon is irradiated with an energy beam in any one of the oxidation treatment, the nitridation treatment, and the oxynitridation treatment. Pattern defect correction method.
(Supplementary note 7) In the step of removing the extra deposit using hydrogen radicals, the extra deposit generated in the step of depositing the carbon-based material containing silicon is removed from the extra deposit. The pattern defect correction method according to any one of appendix 1 to appendix 6, wherein the deposit is removed without being exposed to the atmosphere after the deposit.
(Appendix 8) A source gas supply mechanism for supplying a source gas serving as a silicon supply source and a source gas serving as a carbon supply source to a correction site of a lithography mask in a reduced-pressure atmosphere, and an energy beam for irradiating the correction site with an energy beam An irradiation mechanism, a mechanism for supplying hydrogen radicals to remove excess deposits accompanying the carbon-based correction material containing silicon deposited upon irradiation with the energy beam, and at least one of the correction sites And a mechanism for forming an etching resistant film by oxidizing, nitriding or oxynitriding a part thereof.

DESCRIPTION OF SYMBOLS 11 Processing container 12 Mask stage 13 Mask stage moving mechanism 14 Mask 15 to be corrected 15 Pattern 16 Energy beam irradiation mechanism 17 Source gas supply mechanism 18 Etch-resistant film formation gas supply mechanism 19 Secondary electron detection mechanism 20 Energy beam 21 Secondary electron 22 Defect 23 Source gas 24 Correction material 31 Mixed gas 32 Electron beam column 33 Electron beam 34 Oxygen gas 35 Oxide film 40 Hydrogen radical supply mechanism 41 Halo 42 Hydrogen radical 45 Patch 46 Area where the patch is deposited 51 Vacuum vessel 52 Mask stage 53 Mask stage moving mechanism 54 Mask to be corrected 55 Pattern 56 Electron beam column 57 Source gas supply nozzle 58 Electron beam 59 Secondary electron detector 60 Secondary electron 61 Defect 62 Phenanthrene gas 63 Carbon-based correction material 64 Adsorbed molecular layer 65 Electron Beam induced chemical reaction layer 66 phenanthridine area 73 halo Ren gas molecules 67 scattered electrons 68 carbon modifying material 71 patch 72 patch is deposited

Claims (5)

A carbon-based material containing silicon by energy beam induced chemical vapor deposition by supplying a source gas serving as a silicon supply source and a source gas serving as a carbon supply source to a correction portion of a lithography mask in a reduced-pressure atmosphere and irradiating an energy beam Depositing
Removing excess deposits generated by the step of depositing the silicon-containing carbon-based material using hydrogen radicals;
A pattern defect correcting method including a step of performing any one of oxidation treatment, nitriding treatment, and oxynitriding treatment on at least a part of the carbon-based material containing silicon deposited. The pattern defect correction method according to claim 1, wherein silicon hydride or an organic silicon compound is used as a source gas serving as the silicon supply source . 3. The carbon material containing the deposited silicon is irradiated with an energy beam in the step of performing the oxidation treatment, the nitriding treatment, or the oxynitriding treatment. The pattern defect correction method as described. In the step of removing the extra deposit using hydrogen radicals, the extra deposit is formed by depositing the extra deposit generated in the step of depositing the silicon-containing carbon-based material. 4. The pattern defect correction method according to claim 1, wherein the pattern defect is removed without being exposed to the atmosphere. A raw material gas supply mechanism for supplying a raw material gas serving as a silicon supply source and a raw material gas serving as a carbon supply source to the correction portion of the lithography mask in a reduced pressure atmosphere;
An energy beam irradiation mechanism for irradiating the correction site with an energy beam;
A mechanism for supplying hydrogen radicals to remove excess deposits accompanying the carbon-based correction material containing silicon deposited upon irradiation with the energy beam;
And a mechanism for forming an etching-resistant film by oxidizing, nitriding, or oxynitriding at least a part of the correction portion.

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